This longitudinal follow-up study of childhood-onset depressive disorders, currently in its 9th year, is entering a phase during which all Ss will have reached adolescence; it will thus be possible to observe the transition of a large subgroup of them into adulthood. Given the findings to date, the class of bipolar disorders is also being investigated. The study's developmental scope will be extended to include social competence and other areas of interest in late adolescence and young adulthood. Ss were 8-to-13 years old at intake. Recruitment is complete and includes 142 Ss with affective disorders and 49 age-matched comparisons with non-affective disorders. Drop-out rates have been low (11% for the affective-disorder Ss; 6% for the comparisons). Specific aims include contributions to nosology and developmental psychopathology, with a particular focus on the practical consequences of early-onset disorders. Nosologic goals entail the delineation of the long-term clinical course of childhood-onset depressive and bipolar disorders (e.g., recovery, chronicity, comorbidity); the predictive validity of these diagnoses; and the patterning of episodes and their associated features (including suicidal behaviors). In the sphere of developmental psychopathology, the developmental mediation of clinical course will be examined (e.g., transitions between juvenile and adult disorders, changes in comorbid conditions), and the effects of disorders on the progression of abilities (e.g., social competence, educational and vocational achievement). Other consequences will be examined in terms of rates of hospitalizations, institutionalizations, and incarcerations. A repeated-measures design will be used, with a comprehensive multiperspective assessment battery, including a semistructured psychiatric interview. Diagnoses will be based on the DSM-III. Ss will be evaluated biannually. Salient variables will be assessed independently of each other, and outcomes will be examined in the context of important covariates. This study is the first of its kind to follow children with affective disorders into their adulthood. Thereby, it will contribute to an improved nosology of these disorders a better understanding of the continuities and discontinuities between them and their "adult" counterparts; and will shed further light on the developmental consequences of early-onset pathology, all of which have relevance to early-identification, prevention, and treatment or remediation of these conditions.